1. Field of the Invention
The present invention relates to a recording apparatus and a recording medium used in the recording apparatus.
2. Description of Related Art
Although compact disks (CD) are used as the media to record various data including audio signals, the CD is used only in reproduction. Recently a CD-R disk has been proposed as a recordable medium which can be handled similarly to a CD during reproduction. Data can be recorded on the CD-R disk by a light beam with high and low intensities to the CD-R disk, which is a so-called optical modulation recording. The quality of reproducing the recorded data heavily depends on the light beam of high intensity which causes a change in the recording medium. Intensity of this light beam is optimized by the method described below.
FIG. 1 is a block circuit diagram illustrating a recording apparatus of the prior art. In FIG. 1, numeral 1 denotes a CD-R disk (called "disk" hereafter) used as the recording medium, whereon guide grooves which serve as the targets of applying the converged light beam wobble at nearly constant wobble interval, the time data including the constantly updated minute, second and frame numbers (frame numbers are integers 0 through 74 which divide one second into 75 equal parts) and the standard level (Optimum Power Control) data of the recording light intensity are recorded beforehand as ATIP signals in the form of changes in the intervals.
Numeral 2 denotes a pickup which records and reproduces the data by applying a converged light beam onto the disk 1. Numeral 3 denotes a light detector which converts the light reflected by the disk 1 into an electric signal (current). Numeral 4 denotes an I/V converter which converts the current from the light detector 3 into voltage. Numeral 5 denotes a comparator which carries out binary discrimination of the signal from the I/V converter 4. Numeral 6 denotes a discriminator which determines the duty cycle of the output signal from the comparator 5. Numeral 7 denotes a power controller which controls the intensity of the high-intensity light emitted by the pickup 2 during recording. Numeral 8 denotes a micro-processor. Numeral 9 denotes a decoder which separates the time data from the wobbling of the guide grooves. Numeral 10 denotes a data source which supplies digital data to be recorded. Numeral 11 denotes a memory for temporary storage of the digital signal from the data source 10. Numeral 12 denotes an error controller which generates error control code called CIRC and adds the code to the data to be recorded, which is stored in the memory 11. Numeral 13 denotes a modulator which reads out the data to be recorded from the memory 11 and converts it into an output signal in the signal format called EFM suitable for recording and reproduction, thereby to supply the record signal to the pickup 2. Numeral. 14 denotes a motor which drives the disk 1 to rotate. Numeral 15 denotes a velocity controller which controls the rotation speed of the motor 14 based on the ATIP signal so that the disk 1 turns at a linear velocity that is approximately constant. Numeral 16 denotes a servo circuit which controls the pickup 2 so that the light beam tracks the guide grooves on the disk 1.
The operation will now be described below.
As the first stage of recording, the recording light intensity is determined in the following steps.
(1) Under direction of the microprocessor 8, the pickup 2 is moved into the inner recordable area of the disk 1 to reproduce the disk 1 and separate OPC data from the ATIP signal in the decoder 3, with the OPC data being stored by the micro-processor 8.
(2) The OPC data being stored by the microprocessor 8 is used as the first record signal intensity to set a recording light intensity by controlling the power controller 7.
(3) The first record signal intensity is used to record on the disk 1 for a short period of time.
(4) The signal recorded for a short period of time in the above step is reproduced, to check to see if the recording intensity of the signal is appropriate or not by means of the non-symmetrical signal of the reproduced signal from the discriminator 6.
(5) In case the recording light intensity of the signal is appropriate, the operation proceeds to the second stage (actual recording operation) and, when it is required to alter the recording light intensity, the recording light intensity is changed and the signal is recorded again for a short period and then reproduced.
When the recording light intensity is determined in the first stage, the pickup 2 is moved to the specified recording start position where recording of data onto the disk 1 is started with the determined recording light intensity.
As described above, once the recording light intensity has been determined and the recording operation has started, the light intensity on the CD-R disk is maintained constant until the end of recording. As a consequence, it is difficult to maintain satisfactory quality of reproduced signal if the response (sensitivity) of the recording medium to light intensity is not uniform, or if the effective sensitivity of the disk i varies through variation of wavelength of emitting light from pickup 2 with time.
A recording apparatus is rarely found in the prior art that can record satisfactory signals on the recording media at a different recording speed from that normally specified. Examples related thereto will be described below.
The first example is an analog audio copying (dubbing) apparatus from a compact cassette to another cassette. This apparatus houses a player and a recorder in a single housing to enable an easy dubbing operation. This kind of apparatus is capable of dubbing at a higher speed than the specified speed for the convenience of the user. However, it can handle only analog signals and is not capable of handling digital signals.
The second example is the recording apparatus for digital signals on a digital audio tape (DAT) deck which handles digital audio signals or computer data. The signal recording and reproduction speed of DAT is usually fixed, and recording is carried out only at a specified speed. In this example, the DAT is used in its normal manner. That is, an analog audio signal is converted into a digital signal. And, the signal is recorded on the tape at substantially constant speed. On the other hand, it is desirable that the DAT be able to record such signals as computer data or digital still image data in a shorter period, i.e., at a speed faster than the speed specified in the audio recording. But, as mentioned above, the DAT has a drawback of inability to record in a shorter period.
The third example is the optical disk, represented by the CD, wherein analog or digital data is recorded in the form of pits or the like at a constant linear velocity. In this case, the recording track number of the disk is controlled in accordance with the position of the recording head relative to the disk, while the relative moving speed between the head and the data recording track of the disk is regulated to be constant (1.2 to 1.4 m/sec.). In this example, the rotation speed of the disk with large inertia should be controlled so as to be the proper speed according to the recording position on the disk. When the recording head transfers from a recording position to the start position of recording, a long time is needed to attain the proper rotation speed of the disk due to the disk's large inertia. Thus there is the drawback of requiring a longer wait time before starting the recording operation.